Optical force enhancement and its application to molecular fractionation

Abstract

Controlling molecular external degrees of freedom using optical forces leads to various applications, such as molecule focusing, separation, slowing, and acceleration. Developing a more efficient method, in which lasers of lower powers and intensities are used, is important to enable a variety of experiments. The optical dipole force, which is most widely used for molecule control, is proportional to the molecular polarizability and field gradient and thus can be improved by increasing the field gradient. Efficient deflection of molecules is achieved by employing a tightly focused laser beam or a standing wave composed of two counter-propagating laser beams. We also discuss the application of the enhanced optical force to molecular fractionation with respect to the effective polarizability-to-mass ratios.